1. Field of the Invention
The present invention relates to an imaging device which includes at least one movable optical element and an image sensor, and in particular relates to the structure of a circuit board of such an imaging device.
2. Description of the Related Art
In recent years, imaging devices using an image sensor such as a CCD sensor or a CMOS sensor as an image pickup device instead of sliver-salt film have been in widespread use. Furthermore, a type of imaging device in which a part of the optical elements of an imaging optical system is moved to perform a zooming operation or a focusing operation has also been in widespread use.
However, to improve portability of an electronic device (e.g., a digital camera, a mobile phone, etc.) incorporating such a type of imaging device, there has been a high demand for miniaturization of the imaging device. On the other hand, an imaging device which includes at least one movable optical element is subject to constraints to miniaturization of the optical system provided in the imaging device because an internal space allowing the movable optical element to move needs to be provided. In addition, in the case where an imaging device has such a movable optical element, the drive circuit for the movable optical element may become a source of noise which interferes with signals of picture images, and also the relative position between the drive circuit and the image sensor is subject to some constraints in order to maintain favorable image quality. In other words, it is unfavorable that the drive circuit and the image sensor be positioned too close to each other. Due to such problems, in the type of imaging device which contains an image sensor and at least one movable optical element in particular, it has been difficult to attain a balance between obtaining high-quality images with less noise and miniaturization/simplification of the structure. Conventional imaging devices (for example, Japanese Unexamined Patent Publication 2006-78891, and Japanese Unexamined Patent Publication 2003-5267) are not designed with consideration of both miniaturization and noise-reduction control.